1. Field of the Invention
The present invention relates to an apparatus for adjusting an intermeshing angle (i.e., operating pressure angle or contact angle) in a feed screw mechanism in which rotational movement of a feed screw is transmitted to a pin which is in mesh with the feed screw, so that a linear movement of the pin (i.e., needle, rod or bar) takes place. The present invention also relates to an apparatus which converts the rotational movement of a lead screw to a linear movement so as to move at least one pair of lens assemblies in an optical axis direction thereof. Moreover, the present invention relates to a securing apparatus which secures an image pickup device at a predetermined position.
2. Description of Related Art
In a conventional optical apparatus such as a camera, a feed screw mechanism has been used to convert the rotational movement of a feed (i.e., lead) screw to a linear movement through, for example, a pin which meshes with the feed screw to move a lens assembly or lens assemblies in an optical axis direction. For example, the pin is connected to the lens assemblies of the camera so that the lens assemblies can be moved in the optical axis direction by the rotational movement of the feed screw to carry out a predetermined operation, such as a zooming, etc.
In such a known feed screw mechanism, if the pin does not mesh with the feed screw at an optimal angle, a deviation of the intermeshing position between the needle and the feed screw, from a predetermined position, might occur, resulting in an incorrect axial movement of the lens assemblies.
Furthermore, in the conventional feed screw mechanism, there are two separate feed screws for driving one of a pair of lens assemblies and the other lens assembly, respectively. However, the provision of the separate drivers (i.e., feed screws) for the various components of the associated optical device (camera, etc.) increases the number of necessary components and complicates the structure of the device.
Furthermore, there are known multistage video cameras, electronic still cameras or image scanners, etc., in which a plurality of CCD type or MOS type solid-state image sensors are used, for example, to enhance the resolution. In such cameras, light transmitted through a taking lens is split or separated by a prism, so that the split beams can be received by the respective image sensors. In order to recombine the images detected by the respective image sensors, it is necessary to effect a fine adjustment of the relative position of the image sensors to thereby precisely superimpose the images. In the fine adjustment, one of the image sensors (i.e., first image sensor) is first positioned. Then, the position adjustment of the second image sensor is carried out in accordance with the image detected by the first image sensor, so as to precisely superimpose the first and second images. The same operations are successively carried out for the remaining image sensors.
The position adjustment of the image sensors, as discussed above, is however very complex and requires a complicate adjusting mechanism. Up until now, a simple securing mechanism of an image sensor (or image sensors) which can easily execute the position adjustment has not been provided.